Conventionally, a cooler provided within a heating medium channel through which a heating medium circulates, such as a refrigerant circuit, and configured to cool a heat generating component, such as a power module, with a heating medium circulating through the cooler has been used (see, for example, PATENT DOCUMENT 1). The cooler includes a circular pipe connected to a suction pipe of a refrigerant circuit which performs a vapor compression refrigeration cycle, and forming a portion of the suction pipe, and a heat transfer plate used to mount a power module to the circular pipe. The cooler cools the power module by releasing heat generated from the power module through the heat transfer plate to a low-temperature refrigerant flowing through the circular pipe.